Field of the Invention
The present invention relates to a method for evaluating whether or not a duodenal fluid sample collected from an animal is suitable for detection of pancreatic fluid-derived components, or in other words, whether or not highly reliable results are obtained by using that duodenal fluid sample to detect pancreatic fluid-derived components.
The present application is a U.S. continuation application based on the PCT International Patent Application, PCT/JP2015/055403, filed on Feb. 25, 2015; the contents of which are incorporated herein by reference.
Description of the Related Art
Pancreatic fluid (body fluid discharged from the pancreatic duct) is an important biological sample for determining the status of the pancreas, and is used to test for pancreatic diseases using tests such as cytodiagnosis, bicarbonate measurement, bacteriological examinations, and tests for markers composed of proteins, nucleic acids and the like. In particular, analysis of cells and various biological components contained in pancreatic fluid can be expected to lead to early diagnosis of pancreatic cancer, for which early detection is difficult and which has an extremely poor prognosis.
Pancreatic fluid is typically collected endoscopically from the duodenal papilla by inserting a catheter into the pancreatic duct. However, this method has shortcomings such as being highly invasive for the patient and requiring the acquisition of a high degree of skill by the physician. Therefore, a method has been reported that consists of testing for pancreatic disease using duodenal fluid (body fluid collected from within the duodenum) instead of pancreatic fluid collected from the pancreatic duct (see, for example, PCT International Publication No. WO 2013/038981). Since pancreatic fluid is discharged from the pancreas into the duodenum, pancreatic disease can be tested by detecting pancreatic fluid components present in duodenal fluid. Duodenal fluid does not require an approach to the pancreatic duct during the collection step, and can be collected simply by inserting an endoscope into the duodenum and aspirating duodenal fluid directly. Namely, collection of duodenal fluid can be performed using a lowly invasive and simple procedure in comparison with collecting pancreatic fluid from the pancreatic duct.
In addition to pancreatic fluid discharged from the pancreas, duodenal fluid can contain bile produced in the liver and discharged via the gallbladder, mucus secreted in the duodenum, and gastric juice discharged from the stomach. In other words, duodenal fluid is a body fluid consisting of a mixture of pancreatic fluid, bile, mucus secreted in the duodenum and gastric juice, and the contents of each component vary. Consequently, it is unknown as to whether or not pancreatic fluid, which is considered to provide the most important information in terms of testing for pancreatic disease, is always present in duodenal fluid collected from a test subject. In the case of having collected multiple fractions from the same subject, there is thought to be deviations in the distribution of pancreatic fluid in those fractions, and pancreatic fluid is not necessarily contained in the collected duodenal fluid.
On the other hand, biological components such as proteins are susceptible to degradation and loss of activity. Consequently, in order to obtain highly reliable results, it is important to investigate the quality of biological samples. For example, Japanese Unexamined Patent Application, First Publication No. 2008-506373 discloses a screening method consisting of using a labeled peptide or protein provided with a site cleaved by protease as a standard, adding that standard to a biological sample and then monitoring changes in concentration over time in order to monitor changes and fluctuations in peptide or protein samples present in biological samples such as serum, plasma or whole blood.